1. Field of the Invention
The present invention relates to a liquid discharge head, and more specifically to an inkjet recording head.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2005-125516 discusses an inkjet recording head. The inkjet recording head is configured by bonding an inkjet substrate, on which an electrothermal conversion element is formed, with a supporting member, to connect to an external ink supplying system and to hold the substrate.
In a case where the inkjet recording head is capable of printing in a plurality of colors with one inkjet substrate, it becomes necessary to seal the inks from each other at a bonding section between the inkjet substrate and the supporting member to prevent mixing of the different inks. Further, it becomes necessary to maintain an adequate area of the bonding section to increase reliability of sealing.
Further, in recent years, there is a demand for an inkjet recording method which outputs higher resolution images at higher speed. There is thus a demand to increase the number of nozzles that discharge the inks and to increase discharge frequency.
On the other hand, if the recording speed increases, energy input to the head per unit time and temperature rise of the head during recording increase. If the temperature of the head rises, an ink discharge amount for each page becomes different, so that ink discharge becomes unstable at high temperature. Further, continuous recording performance may be lowered.
Japanese Patent Application Laid-Open No. 2005-125516 discusses an inkjet recording head in which the inkjet substrate is fixed to the supporting member, so that the heat generated in the inkjet substrate is diffused to the supporting member. The temperature rise in the inkjet recording head can thus be reduced by increasing the area of the bonding section between the inkjet substrate and the supporting member (hereinafter referred to as a ground contact area).
However, if the ground contact area between the inkjet substrate and the supporting member is increased to reduce the temperature rise in the inkjet recording head, the size of the inkjet substrate becomes large, so that productivity is reduced.
To solve such a problem, the entire inkjet substrate may be thinned. In other words, the size of an opening of an ink supply port can be decreased by thinning the entire inkjet substrate. The ground contact area between the inkjet substrate and the supporting member can thus be secured without increasing the size of the inkjet substrate.
However, if such a method is selected, the strength of the inkjet substrate is decreased, so that warpage is generated in the inkjet substrate due to a stress of a flow path forming member. In such a case, the productivity is greatly reduced.